A range of 3 to 5 miles and 2 Mbit/s was closer to reality. In fact, one of AT&T's three deployments rarely saw throughput rise above 500 kbit/s, he said.

Where WiMAX would prosper, he predicted, was in moving backhaul traffic. But its potential users had slightly surprising desires and concerns.

AT&T's existing business customers were looking for improvements in cost, diversity, reliability, availability and provisioning time. Speed came well down their list of reasons for deployment. Their main concerns were security, reach and the fact that WiMAX is an unproven technology.

AT&T has three trials using a combination of licensed and unlicensed spectrum. A Middletown trial using a pre-specification agreement linked three businesses, with favorable results. Up in Alaska, WiMAX is being deployed in five village locations. Not all of which have running water - but are now being given broadband internet. AT&T had opted for unlicensed spectrum because there was little electromagnetic pollution. Not surprisingly, the Alaskans were delighted with going from no net to broadband. A third deployment is taking place in Atlanta.

But if WiMAX makes any impact it will be for cheap local loops. AT&T's current fibre carrier customers, who need no more than 1.5Mbit/s, appreciate the flexibility of WiMAX and spend a lot of money today on access charges.

It's very early days, and it was sobering to be reminded that the first, proprietary line of sight wireless networks were being announced in 1996, and we're still deploying them. ®